This invention relates to sealing the area between a terminated conduit and a cable that egresses therefrom.
Fiber optic cables have become a preferred transmission system for telecommunication and data communication. A cable can contain many strands of optic fibers. These cables are generally installed underground inside a conduit. The conduit and the cable that runs through it are often laid in trenches and can extend for long distances. For purposes of maintenance, upgrading, and connection to the fiber optics, underground vaults are installed strategically along the path of the conduit and cable. Many cables and conduits may terminate or run through these vaults or other similar compartments. When a conduit terminates, but the cable continues its run, it is desirable to provide a seal between the cable and the conduit at the termination of the conduit. This seal prevents contaminants from entering the space between the cable and the conduit and thereby avoids possible deterioration of the fiber optic cable and its contents.
Schemes to effect this seal are easily provided if both the conduit and cable terminate in close proximity of each other. In this case, the seal is formed by a gasket and supporting structure. The gasket and its supports can slide axially over the cable and into the conduit. This is not the case if the end of the cable is not accessible. In this case the gasket and its supports must be split or halved in order to surround the cable. Such a seal is described in U.S. Pat. No. 4,842,364. The device described requires intricate fabrication techniques that utilize split threaded devices used for producing compression force on a gasket, thus causing the gasket to expand. The threaded nut is made in two halves and must be assembled around the cable. During fabrication of this nut, significant effort must be given to the correct timing of the threads so that when assembled the mating halves will produce a continuous thread. Assembly of the split halves can be difficult. In this prior art, the majority of the assembly of the seal occurs at the installation site, in the confines of an underground vault, which is difficult because the pieces are small and intricate. If the threaded parts are made of plastic, the tooling to produce these parts is intricate, complicated, and expensive. The amount of compression of the gasket in this and other prior art is dependent on how tightly threaded members are torqued. Since this torque is uncontrolled, large forces may be transmitted which may damage the conduit and/or cable. Conversely, if too little torque is applied, the gasket may not seal as intended. Some prior art use metal fasteners as part of the scheme to compress a gasket. Metal may corrode after time.
Accordingly, it is the object of this invention to provide a simple, cost effective means to seal the area around a cable and the conduit in which the cable resides. The advantages are:
(a) extreme ease of installation
(b) low cost
(c) complete assembly ease prior to installation
(d) controlled force that is transmitted to the cable and conduit
(e) excellent sealing between cable and conduit
(f) resistance to chemicals in its environment
(g) inherent corrosion resistance
Still further objectives and advantages will become apparent from a consideration of the ensuing description.
In accordance with the present invention the seal between the cable and the conduit is effected when a gasket is compressed or expanded by the simple means of rotating a cam member into a locked position.